Radio frequency identification (RFID) devices are well known and are increasingly utilized in a wide variety of applications. However, one challenge associated with RFID devices (e.g., RFID tags, RFID labels, RFID chips, RFID straps, or RFID inlays) is the manufacture and testing of the RFID devices in a high-volume and cost-effective manner.
For example, during or after the manufacturing process, the RFID devices may be tested while located in close proximity to each other (e.g., adjacent RFID devices closely spaced). The RFID devices, as an example, may be manufactured on a common carrier web, with the RFID device (e.g., an RFID inlay) having its antenna mounted on the common carrier web and its integrated circuit mounted to the antenna.
Due to the close proximity of the RFID devices, it may be difficult to establish bi-directional communication with each of the RFID devices during testing. In general, an antenna of the RFID device may be viewed as having a near field region and a far field region. The near field region refers to a reactive near field (e.g., approximately R≦λ/2π) and a radiating near field (e.g., approximately R<2D2/λ), while the far field region refers to a radiating far-field component (e.g., R>2D2/λ), where R is the distance from the antenna and D is the largest dimension of the antenna. Short-range testing of RFID devices generally involves testing within the near field region (e.g., utilizing the near or far-field components), while long-range testing generally involves testing within the far field region.
For short-range testing and long-range testing, typically certain precautions must be taken, when testing one of the RFID devices, to prevent the RFID devices that are in close proximity from also responding or affecting the test results for each RFID device being tested. This results in complicated test procedures or test setups and may lead to operational RFID devices that are tested and erroneously determined to be defective. As a result, there is a need for improved test techniques for RFID devices.